Plungers have been used heretofore for lifting, recovering, and/or removing oil, water, or other fluids from well casings and other tubulars. In some wells, due to relatively low formation pressures and/or other formation conditions, liquids tend to accumulate at some level within the well casing rather than flowing naturally to the surface. Plungers offer potential benefits over conventional pumps, submersible pumps, and other power-operated devices for recovering or removing such fluids.
Various types of plunger devices are known in the art. By way of example, one common type of plunger comprises: an elongate housing assembly; one or more external sealing devices which can be actuated to sealingly contact the interior wall of the well casing; a flow passage extending through the housing assembly; and a valve for opening and closing the flow passage.
When using a well plunger, a lubricator assembly is typically installed above ground at the wellhead for receiving and retaining the plunger between production cycles. At the beginning of the production cycle, the plunger is dropped from the lubricator assembly with the plunger valve in open position. The fluid in the well casing or tubular is thus allowed to flow through the interior flow passage so that the plunger will drop through the fluid to a stop structure installed at a desired downhole position.
The plunger will typically be configured such that, upon striking the downhole stop structure, the plunger valve will automatically close and the external seal(s) will be urged into contact with the interior wall of the tubular. With the tubular sealed in this manner, the pressure beneath the plunger will eventually increase to the point that the plunger will begin to rise, thus lifting the column of fluid on top of the plunger toward the surface and into an overhead production line.
Upon reaching the top of the well, the plunger is again received in the lubricator assembly. The lubricator assembly will typically include an interior actuator which automatically operates to open the plunger valve and release or retract the plunger seal(s). The lubricator assembly will also typically include an interior latch mechanism which will releasably grasp and hold the plunger at the top of the well until it is time to drop the plunger into the well for another production cycle.
The lubricator assembly will typically comprise (a) a lower portion such as an adapter which is installed on the well casing or other tubular above ground at the well head and (b) an upper riser which is removably installed on the upper end of the adapter. The upper riser can be detached from the adapter for removing, servicing, and/or replacing the plunger.
The lubricator assemblies used heretofore for plungers and other downhole tools have had significant shortcomings. The riser segment of a typical lubricator assembly can weigh in the range of from about 50 to about 350 pounds. Thus, the removal, lifting, alignment, and reattachment of the riser can be very difficult and hazardous and often requires the use of a hoist or other lifting device which must be transported to the well site. To assist in handling the riser, it has been suggested that a hinge be installed between the adapter and the riser. However, even with the use of a hinge, the weight and size of the riser element is typically such that it is still difficult to lift the riser off of and on to the adapter and to hold the riser in precise alignment for reattachment.